The present invention relates to a process and a facility for treating solid waste materials to separate out and recover usable materials and for forming a commercial compost from a recoverable biodegradable waste material fraction.
Solid waste materials such as household garbage and commercial trash from retail establishments, apartments, offices and warehouses have traditionally presented problems of disposal. These problems have become increasingly critical in recent years as a result of a rapidly increasing population and a dramatic increase in the per capita production of solid waste. Additional disposal problems have been created by the change in character or composition of municipal waste as a result of the movement away from metal, wood and glass packaging toward paper and plastic packaging.
Currently solid waste is disposed of by incineration and/or land fill. Incineration is rapidly becoming a non-viable alternative in heavily populated areas. The public outcries against air pollution from the burning of waste materials has halted nearly all new incinerator construction. Similar problems surround new landfills. Environmental restrictions as well as land usage demands for housing have reduced the number of sites available for landfills.
In response to these waste disposal problems, both the government and the public have demanded that wherever possible recycling be employed both to conserve material resources and to reduce pollution problems. Efforts have been made to recover valuable resources such as glass, plastic, paper, aluminum and ferrous metals from waste materials. A variety of systems and techniques for recovering these resources from solid waste materials have been developed. U.S. Pat. Nos. 3,738,483 to MacKenzie, 3,925,198 to Eckhoff et al., 4,077,847 to Choi et al., 4,187,775 to Flender, 4,341,353 to Hamilton et al., and 4,553,977 to Fry as well as Netherlands Patent No. 8401119 illustrate some of the known systems for separating and recovering recyclable materials contained in municipal and/or industrial waste.
While most systems are designed to recover as many recyclable materials as possible, some are designed to recover specific materials and/or form specific products. U.S. Pat. Nos. 3,557,685 to Schoering, 3,741,863 to Brooks, and 4,460,131 to Cerroni for example illustrate systems and processes for recovering paper products, cardboard and/or other types of waste cellulosic materials. U.S. Pat. No. 4,065,282 to Morey illustrates a method for recovering glass from municipal waste.
Some systems take a recovered fraction and process it into fuel or some other useful product. U.S. Pat. No. 3,524,594 to Anderson et al. for example transfers a remaining refuse portion containing organic waste to digester tanks for composting. U.S. Pat. No. 4,264,352 to Houser illustrates a system for separating out various waste material fractions and for converting a recovered wetted paper fraction into a compost.
The components in each of these systems are specifically arranged and designed to recover certain individual fractions such as combustible organic materials, aluminum, ferrous metals, glass plastic, and miscellaneous bulky inorganic material. Efficient resource recovery depends upon separating the maximum amount of desirable material from the refuse using relatively few separating components. It also depends upon minimizing the percentage of unwanted materials in the individual fractions.
Accordingly, it is an object of the present invention to provide an economically viable, efficient process for treating solid waste material to separate out and recover recyclable materials.
It is a further object of the present invention to provide a process as above for forming a commercially useful compost from biodegradable waste products and other useful inert materials recovered from the treated waste material.
It is yet another object of the present invention to provide a zero discharge facility for performing the above process.
It is still another object of the present invention to provide a process and a facility as above which have a minimal environmental impact.
These and other objects and advantages will become more apparent from the following description and drawings.